The invention present relates to a base station for a radio communication system, a base station system and a mobile radio system with at least two transceiver means.
Radio communication systems are formed by mobile radio systems, wireless telephony systems, or radio stations for wireless extension (RITL radio in the local loop), for example. Mobile radio systems enable the setup of communication connections to mobile subscribers, while radio stations for wireless extension set up communication connections to stationary subscribers. A radio station at the network side is referred to as a base station.
Communication connections are set up and maintained in that signalling information and useful information is communicated via a radio interface. If a number of subscribers on the same carrier frequency of this radio interface are separated by different time slots, this is a time division multiple access system. The time division multiple access method is also referred to as TDMA (Time Division Multiple Access).
One known mobile radio system is the GSM (Global System for Global Communication) mobile radio network, for example. In addition to time division multiple access, other methods for separating the subscribers can additionally be used at the air interface. In the GSM mobile radio system, a frequency division multiplex system is also available. Alternatively or additionally to these methods for subscriber separation, specific codes can also be used for each communication connection.
A base station is a remote unit which is connected to other network components in a wirebound fashion at the network side and which is connected to the terminal equipment, or to another radio station via a radio interface. The power consumption of this type of base station is 2 kW, for example. This value is largely independent of the actual traffic volume in a radio area covered by the base station.
International Patent Application No. WO-A-94/2239 teaches a base station for a radio communication system which comprises a number of transceiver means and which serves for the radio-technical supply of communication connections from/to mobile stations in a serviced radio region. The transceiver means are supported by a main power supply. For various emergencies, caused by overheating, fire and power outage in the base station, for example, (the last case being prevented by the use of a substitute power supply (backup source)), a reduction of the power consumption for the base station is desirable. For this purpose, a control means in the base station either deactivates a variable number of transceiver means during an interruption of the power supply, or it holds them in a standby state, in which they consume less power. The deactivation preferably occurs gradually in several chronologically consecutive stages in which, first, a comparison of the number of transceiver means to a predefined value is performed, and second the transceiver means are deactivated depending on the result of the comparison.
International Patent Application No. WO-A-94128644 discloses a typical radio communication system with base stations, at least one base station controller, and an operations and maintenance center at the network side. The base station contains transceivers which are connected to an antenna unit, as well as a base-station-related local operations and maintenance unit. In the base station, a control unit handles the selective switching of a transceiver means to a communication connection. The transceivers can be automatically controlled either by the base station controller, the network-side operations and maintenance center, or by the base-station-related operations and maintenance unit, so that they are in an operative state or in a stop state, respectively. The transceivers that are not needed are deactivated in order to reduce power consumption.
It is the object of an invention to provide a base station which can be operated more economically, in cooperation with other network components of a radio communication system, as warranted. This object is inventively achieved in accordance with the invention.
A base station for a radio communication system contains at least one transceiver and at least one antenna for the radio-technical supplying of communication connections to at least one remote station. Furthermore, the base station contains a controller for monitoring and organizing the transceiver and for switching a transceiver into an energy saving mode as soon as the load of a remaining transceiver is less than or equal to a threshold value. It is inventively taken into account that the load of a base station can change very rapidly and it should therefore be possible to supply at least one additional communication connection on a remaining transceiver which is deactivated, without requiring the transceivers which are switched into the energy saving mode.
By this measure, it is possible for the base station to return a transceiver to full functionality from the energy saving mode over a definite time-span. The complete radio-technical supplying of communication connections to remote stations is thus still guaranteed.
The base station can thus respond to the sharp load fluctuations of a radio communication system, e.g. of a mobile radio network, and can adapt its functionality in times of lower traffic volume. Furthermore, a lower energy consumption for the base station is possible on the basis of switching into an energy saving mode. Further advantages emerge from a reduced cooling outlay.
The costs of the energy supply compared to the installation costs of a base station are growing ever more important for operators of a mobile radio network. The inventive base station allows the operator of such a mobile radio network to save operating costs and to offer his or her services more economically. Likewise, the switching of transceivers into the energy saving mode leads to a reduction of interferences in the radio communication system, thereby improving speech quality under certain circumstances.
According to a further development of the invention, the reliability of the radio-technical coverage is further increased in that a transceiver is switched into the energy saving mode only given the presence of a substitute transceiver for an executive channel. By monitoring and allocating communication connections to transceivers, the controller provides that a first transceiver is always operative for an executive channel and that a second transceiver is always operative as a replacement for this, while other transceivers are switched into the energy saving mode given a correspondingly low traffic load.
Even given a sudden failure of the transceivers for the executive channel, an executive channel is continuously available to the remote stations by means of a changeover to the substitute transceiver which. Additional transceiver means are advantageously not completely deactivated, but rather, in the energy saving mode, they consume a mere minimum of energy that is needed for preheating and maintaining control units for starting the transceiver in a few seconds.
Another advantageous development of the invention provides a base station with a cell sectoring wherein at least one transceiver is allocated to each sector by the controller. Preferably, that transceiver which has the largest area of coverage is switched into the energy saving mode. This is particularly advantageous if a transceivers can be connected for a number of sectors of a cell or for all sectors. In contrast to transceivers which are sector-bound, a transceivers which is additionally allocated to the sector or sectors in particular traffic peaks is preferably deactivated given an abatement of the traffic load. On the basis of this development, it is possible to suppress overload peaks for base stations without having to provide transceivers with continuous maximum energy consumption.
The energy saving mode can be designed such that all the functions of the base station are deactivated until controlling occurs for purposes of a renewed startup of the base station. This is of particular importance if the base station is implemented for what is known as a microcell, i.e. of a small cell which is located inside a larger cell (hierarchical cell structures). Such microcells are needed for expanding capacity, though this capacity expansion is necessary only at peak load times.
Outside of these peak load times, this base station with only one transceiver, for example, can be completely deactivated. This potentially eliminates the costs for a dedicated line (dialable ISDN) between the base station and a base station controller, which can be cleared in this case. With the base station for the larger cell (umbrella cell), this type of base station for a microcell forms a base station with at least two transceivers. The controller is formed by the base station controller, for example.
Within a base station, it can also be provided that only the functions of the transmittier are deactivated. Transmitters have a high energy consumption, so that their deactivation is particularly advantageous. In addition to transmitters, means for ventilation, for signal processing, for power supply and for control can be deactivated, as well as means for reception.
An inventive base station system with at least one such base station also contains a base station controller, which is connected to a number of base stations, for organizing the radio-technical coverage and for distributing the communication connections to the transceiver such that a transceiver is switched into an energy saving mode as soon as the load of a remaining transceiver is less than or equal to a threshold value. A base station controller can monitor and valuate the radio relations in a number of cells, so that an organization of the radio-technical coverage is possible, via one base station, and an optimally large number of transceivers can be switched into the energy saving mode.
In order to continuously offer at least the executive channel for each base station, according to another development of the inventive base station system, an optimally large number of communication connections are allocated to a transceiver, which also realizes the executive channel. As this transceiver is prioritized in the allocation of communication connections, other transceivers become free, the deactivation of which is provided without any restrictions.
According to another development of the invention, the radio communication system is implemented as a mobile radio system and contains at least one mobile switching center which is connected to at least one base station system. In addition, the mobile radio system contains at least one operations and maintenance center for evaluating information about the load of transceivers of various base stations and for setting a respective threshold value in reference to the deactivation of additional transceivers.
This makes possible an individual setting for all base stations, which setting satisfies the local conditions for the equipping of base stations and for the individual cells, respectively. In particular, the threshold values can be set such that new communication connections to be set up are allocated first to cells with greater reach, or with higher traffic capacity, and a renewed activation of transceivers for microcells in hierarchical cell structures occurs later.